Ecological determinants of the occurrence of Hedera helix L.

Ivy (Hedera helix L.) is the only native evergreen climber and exclusive representative of Araliaceae in Poland's flora. It occurs in all forests across Poland, mainly in the western and the southern part of the country. It is a shade-tolerant species, preferring mild climate as well as moist and fertile soils. In favourable conditions ivy climbs up the various supports, and it blooms when it has sufficient access to the light. The study synthesises dispersed information on the ivy ecology and identifies areas for further research. The occurrence of ivy is determined mainly by environmental conditions. Plantings and uncontrolled penetration into the forest environment plays also an important role in this species spread. Gaps, which have arisen in the stand, increase the chances of intensive growth of ivy population. The possibility of colonization of this species is limited mainly to secondary forests. Most studies suggest that ivy is influenced, indifferently or preferably, on tree support, provided that they are not weak. There are some disturbances such as storms or timber harvest that can contribute to the creation of favourable conditions for the mass colonization of forest habitats by ivy. The data concerning dynamics of ivy growth comes from research conducted in the Rhine valley and the Mediterranean region i.e. areas which have the most favourable conditions for the development of the species. Such research have not been carried out in the Central and Eastern Europe, where less favourable conditions for the development of ivy occur.